从angular13中的服务中获取未定义的值

Question

**Iam在服务中使用POST方法函数，调用sendingcomponent中的函数，保存服务变量中的响应，并将该变量发送给receivingcomponent，并将数据分配给另一个变量，但得到一个未定义的值i接收组件**

sending.component.ts

import{sharedservice}....
constructor(private services:sharedservice)
ngOnInit(){
this.formvalue()
}
this.formvalue(){
this.services.getdata(this.form.value)
}

shared.services.ts

import{Httpclient}....
@Injectable()
dataofservice:any;
constructor(private http:httpClient)
this.getdata(data:any){
this.http.post('http://localhost:3002/data')
.subscribe(res =>{
this.dataofservice= res   
console.log(this.dataofservice) -->(here I am getting the value)
})
}

receiving.component.ts

import{sharedservice}....
constructor(private services:sharedservice)
datatostore:any;
ngOnInit(){
this.datatostore = this.services.dataofservice  
console.log(this.datatostore)-->(here I am getting value as UNDEFINED)
}

预先感谢

Answer 1

我不建议订阅服务，让服务返回observable。此外，根据您的方法，您可以使用subject或类似的方法来通知您的receiving组件。

import{Httpclient}....
@Injectable()
export class YourService {
   private dataofservice = new BehaviorSubject<any>({});
  
   constructor(private http: httpClient)
   
   this.getdata(data: any): Observable<any> {
      return this.http.post('http://localhost:3002/data').pipe(
         tap(response => this.dataofservice.next(response))
      );
   })

   getDataOfService(): Observable<any> {
      return this.dataofservice.asObservable();
   }
}

发送组件

constructor(private services:sharedservice) {}

ngOnInit() {
   this.formvalue()
}

formvalue() {
  this.services.getdata(this.form.value)
   .subscribe(console.log); // your data is here
}

接收组件

...
 constructor(private services:sharedservice) {}
   
  ngOnInit() {
    this.services.getDataOfService(data)
     .subscribe((response) => console.log(response)) // and here as well
  }